I forget how it scales, but the point remains for whatever box volume gives the same excursion at the same freq.

I think it's linear to first order; twice the box volume gives half the air spring stiffness, and I suspect is still way stiffer than the driver siuspension.

I'd go for it. Personally, I think with eight 21's I'd be okay with SPL across the whole bandwidth. Using 2.2kw instead of twice that would be easier on the coil but only depending on use. Using a larger box just means more Xmax down low for the most part. I've compared the 4.4kw 4cuft design and the 2.2kw 6cuft (per driver) design and they are pretty close with the edge in total output going to the smaller on, of course.

Both are good options. I was just looking for the best way he could maximize output and extension but using a larger cab with less power won't hurt. There's a balancing point though and at a certain point you will have large box that requires some form of filter or limiter and for those looking for maximum bandwidth.... those are bad words and are needless complications to a system, imho.

AVH, another option for you would be 6cuft and use 2,200w per driver. It's slightly bigger box than what I had suggested and uses half the power. You're looking at a 24" cube for each driver like this. This is a nice option that saves you $$$$ on amps and I know you were concerned about thermal buildup so if that is something you don't want to think about, try Noah's option.

Wood is cheap. Both options are SIGNIFICANTLY less complicated that building a limited bandwidth horn/vented system but it all comes down to what you want so... follow your hearth. Lol.

Unless box size is an issue (you mentioned 55 cf so I assume it's not), I don't understand why you wouldn't use half the amp power and twice the box.

Saves stress on the driver too; 4 cf seems awfully small for a 21 with that displacement.

You only need to increase each dimension by 1.26X to double the volume.

Originally I had soho design horns for Malx 21s way I could get high spl from 30hz on up and use a large enclosure for 12 IB18s for high spl below 35hz. Well the IB18s had unknown eta dates so I preordered the 8 mach 5 21s to take the place of the IB18s. Well, I dont have anywhere near enough space to do the IB with the mach 5 21s so if they are going to be able to have high spl from 35hz on up then I can do away with the FLH mal x 21s. 8 mach 5s model at 146db from around 55hz on up with the small enclosures and 140db with say 7 cuft enclosures. That would mean that the horns with the mals would still be needed to reach the 145db range up high if I dont use the small enclosures.

1. 10 21s- 8 mach 5s and 2 malxs in small enclosures with 5 FP14000 (3 220v and 2 110v). Dont know how the mix between the 2 voltages will affect things as the 110s would be on dedicated 20 amps circuits each.

2. 10 21s- 8 mach 5s in large enclosures and 2 malx FLHs with 2 FP14000s 220v and one QSC2450 on the horns

I'd go for it. Personally, I think with eight 21's I'd be okay with SPL across the whole bandwidth. Using 2.2kw instead of twice that would be easier on the coil but only depending on use. Using a larger box just means more Xmax down low for the most part. I've compared the 4.4kw 4cuft design and the 2.2kw 6cuft (per driver) design and they are pretty close with the edge in total output going to the smaller on, of course.

Both are good options. I was just looking for the best way he could maximize output and extension but using a larger cab with less power won't hurt. There's a balancing point though and at a certain point you will have large box that requires some form of filter or limiter and for those looking for maximum bandwidth.... those are bad words and are needless complications to a system, imho.

AVH, another option for you would be 6cuft and use 2,200w per driver. It's slightly bigger box than what I had suggested and uses half the power. You're looking at a 24" cube for each driver like this. This is a nice option that saves you $$$$ on amps and I know you were concerned about thermal buildup so if that is something you don't want to think about, try Noah's option.

Wood is cheap. Both options are SIGNIFICANTLY less complicated that building a limited bandwidth horn/vented system but it all comes down to what you want so... follow your hearth. Lol.

Yeah 2200 per driver would be nice if they could be wired to make purchasing fewer amps possible. I've looked at every wiring diagram for single 4ohm voice coils and I just cant take advantage of buying two FP14000s and get more power to each sub because of not being able to run 4ohm bridged mode.

I am selling my FP10Q. It is an awesome amp. I need a FP14k bridged for my next system but if I had 4 subs this is great for running per channel to each sub. I was going to buy another FP10Q and use 2 but that is not needed.

Get 10000Q's instead and then bridge each channel pair for 4,200w each @ 8 ohms.

Bam!

Yeah I remember there only being a little difference in roll off. Thats a great idea. I've got the mdf baffle cut, rear panel, and now going to cut the top, bottom and sides for just over 6cuft each way after bracing it will be right around 6 even. That models pretty well! Shows hitting 40mm at 2.6hz.

I am selling my FP10Q. It is an awesome amp. I need a FP14k bridged for my next system but if I had 4 subs this is great for running per channel to each sub. I was going to buy another FP10Q and use 2 but that is not needed.

When everything is built, hooked up and running at 140-145db, I wanna see that YouTube video of you sitting in your Home Theater for a half hour "enjoying" the experience.
It'll never happen.

Well the 30 minute video will never happen but I bet whatever you wanna bet that I'll be enjoying it in way more than 30 minute spurts!!!

I had a $25k stereo in a Jimmy 4x4 that was pushing 155-156 at the dash with the windows up that I literally listened to for hours upon hours at a time. I do have some hearing loss now but hay, ya only live once! So, considering that I'll have my recliner right there a few yards away from Sam Adams on tap, I dont see 30 minutes being much of a session!

Well, Thanks Scott! I've managed to get the mdf baffle cut and 4 sub holes routed out, the bottom panel, top panel, back panel, and some bracing all cut in the past couple hours. About to start glueing and clamping after finish feeding the baby.

Thanks again Scott and Noah! One box for 4 is about 75% complete. Now this thread can die. I'm gonna update the build thread.

Heheh, nice! So one big enclosure for all four 21's? Wow! That should.... be really heavy.

Yeah I really dont want to know so after I get the front, top, and bottom panels together I'm gonna move it to its final resting place before finishing it! I had the carpet installers come measure today and havent decided if Im gonna build the baffle wall and or screen wall on top of the carpet or not. I may just put some insulation boards down just for the baffle wall leaving carpet between the baffle and false screen wall.

To test the electronics roll off you could run rew straight thru the chain with REW. You could see exactly the roll off and input the figures in winisd and come up with an actual set of numbers to shoot for and be worry free.

I hope you have a dual-leg 100amp 120v service because 4 of them (2x2) will draw somewhere between 20-60amps per leg RMS and with peaks up to 150amps per leg.
i.e 40-120amps continous and 300amps total peak.

Your power bill will be at least $100 higher per month, I guarantee it.

A 120/20amp circuit breaker trips at 2 channels of 1200watts RMS after about 5 seconds duty.

A 120/30amp circuit breaker trips at 2 channels of 1800watts RMS after about 5 seconds duty.

For 240v double it.

If you're not popping them then you are not exceeding those watts long term PERIOD.

The 2 channels of 4400watts is burst-power folks, not RMS.

The REAL (not cloned) LG14K, PS10K, IT8K/12K etc etc; none of these amps will sustain the long-term RMS values you guys are talking about, they all engage limiters to keep the power transistors from melting.

Even then I'm ALMOST CERTAIN you will give up before 8x21's and 4x14K's will or at least your house or wife will... and you can take that to the bank!

I hope you have a dual-leg 100amp 120v service because 4 of them (2x2) will draw somewhere between 20-60amps per leg RMS and with peaks up to 150amps per leg.
i.e 40-120amps continous and 300amps total peak.

Your power bill will be at least $100 higher per month, I guarantee it.

A 120/20amp circuit breaker trips at 2 channels of 1200watts RMS after about 5 seconds duty.

A 120/30amp circuit breaker trips at 2 channels of 1800watts RMS after about 5 seconds duty.

For 240v double it.

If you're not popping them then you are not exceeding those watts long term PERIOD.

The 2 channels of 4400watts is burst-power folks, not RMS.

The REAL (not cloned) LG14K, PS10K, IT8K/12K etc etc; none of these amps will sustain the long-term RMS values you guys are talking about, they all engage limiters to keep the power transistors from melting.

Even then I'm ALMOST CERTAIN you will give up before 8x21's and 4x14K's will or at least your house or wife will... and you can take that to the bank!

lol, there is no way his power bill is going to be an extra $100 a month. I have double the power he has and even if if I watch movies every second night at reference, it's still only about $20-30 more. He's not going to have the system cranked 24/7.

Another thing to note, when I attempted to bridge my IT8K into a single LMS-18 at 4-ohm...

The amp was just idling along at -30db but I felt that the cone was on the verge of exceeding its 80mm or fry at a mere moments notice if any sort of half decently strong or low hz type signal came along; the overhead potential in that mode was down right scary folks I am dead serious.

I know for a fact it outputs a solid 1500-2000 real RMS watts and bursts up to 8000watts in that mode. I have it on a 240v/15amp breaker FYI.

I had to turn off bridging and drop it back down to 2-ch mode to avoid its impending death. Any lesser of a subwoofer would have died, I guarantee it.

I hope you have a dual-leg 100amp 120v service because 4 of them (2x2) will draw somewhere between 20-60amps per leg RMS and with peaks up to 150amps per leg.
i.e 40-120amps continous and 300amps total peak.

Your power bill will be at least $100 higher per month, I guarantee it.

A 120/20amp circuit breaker trips at 2 channels of 1200watts RMS after about 5 seconds duty.

A 120/30amp circuit breaker trips at 2 channels of 1800watts RMS after about 5 seconds duty.

For 240v double it.

If you're not popping them then you are not exceeding those watts long term PERIOD.

The 2 channels of 4400watts is burst-power folks, not RMS.

The REAL (not cloned) LG14K, PS10K, IT8K/12K etc etc; none of these amps will sustain the long-term RMS values you guys are talking about, they all engage limiters to keep the power transistors from melting.

Even then I'm ALMOST CERTAIN you will give up before 8x21's and 4x14K's will or at least your house or wife will... and you can take that to the bank!

Its 3 220v 10000s for 10 21s in 7cuft cabs. It was 8 until matched medium enclosures with medium power so added the other 2 malx 21s to match.

As far as electrical I am ignorant but paid the power company to run a 400 amp service and had the electricians run #6 to the media closet for 3 20amp 220v lines along with a bunch of 110v dedicated circuits. Heres the closet

As far as the room handling it, everything is glued and screwed, 4 troughs in ceiling on joists, and over 10x the amount of drywall screws. I built it from ground up knowing what was going in it. Handling the pressure isnt a big deal it wont be nearly as loud as vehicles.

You have the equivalent of 8 14K's N8DOGG? Nice!!!
Dude, what exactly are you doing with that much power?

2 x 14k clones (2 more on the way) 8 x ep4000's and a rmx 5050. Pretty close to double if not more. All on 8 x 20A lines, 2 x 30A lines for the 14's and the next 2 14's will be 220v. Power is a wonderful thing lol

Its 3 220v 10000s for 10 21s in 7cuft cabs. It was 8 until matched medium enclosures with medium power so added the other 2 malx 21s to match.

As far as electrical I am ignorant but paid the power company to run a 400 amp service and had the electricians run #6 to the media closet for 3 20amp 220v lines along with a bunch of 110v dedicated circuits. Heres the closet

As far as the room handling it, everything is glued and screwed, 4 troughs in ceiling on joists, and over 10x the amount of drywall screws. I built it from ground up knowing what was going in it. Handling the pressure isnt a big deal it wont be nearly as loud as vehicles.

That is awesome!!!!!!!!!!!!! I had to get a second 200A service installed but it's fairly far away from my HT area. Thats is the way to go.

That is awesome!!!!!!!!!!!!! I had to get a second 200A service installed but it's fairly far away from my HT area. Thats is the way to go.

Yeah they screwed up 3 times when I was changing my service. First time they showed up and asked me why they were sent.

Second time my electrician was here to meet them and they approved the wrong meter base.

Third time they werent prepared to pull the new 400 amp line. Only had one truck. Then told me they were gonna disconnect my power if didnt change meter base to the ones they like to use because they were switching over. My neighbors have the same base I had to pay my electrician to install, uninstall and buy the other one.

It was one big fiasco. Oh well, I now have the power I need. It could get hairy when all three AC units are running along with all the pool stuff and theater eek!!!! Lets hope not but possible. I do have 9 dedicated circuits in the closet for the theater tho so I'll always be able to have audio even if have to turn off the AC in the main house lol

I just finished putting the bottom of the 4 sub enclosure on and now have the back and sides to go along with a few more braces.

I'd be curious to know how the higher voltage versions do comparatively when you get them hooked up.

If better, then I'll def be saving up for them in my future. I'm always looking for the best bargain around; and from what everyone keeps saying the clones seem to be it.

Yeah I'll find out soon enough but only the ear test for me. I made the enclosures 7 cuft because I doubted the 10000s would really put out the 2100 watts per driver especially down under 10hz. I modeled them hitting xmax at 6hz I think exactly. So if they bottom out then I under estimated the clones. I had to make the mal boxes a tad smaller which wasnt a problem as I already had two to work with.

I havent looked but is there another amp that I could hook the 2 mals up to to match the 10000s in 8 ohm bridged mode as I'll be wasting a channel on one 10000